Record warmth in Atlantic Main Development Region for hurricanes

By: Dr. Jeff Masters , 4:52 PM GMT on March 08, 2010

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Sea Surface Temperatures (SSTs) in the Atlantic's Main Development Region for hurricanes were at their highest February level on record last month, according to an analysis of historical SST data from the UK Hadley Center. SST data goes back to 1850, though there is much missing data before 1910 and during WWI and WWII. The region between 10°N and 20°N, between the coast of Africa and Central America, is called the Main Development Region (MDR) because virtually all African waves originate in this region. These African waves account for 85% of all Atlantic major hurricanes and 60% of all named storms. When SSTs in the MDR are much above average during hurricane season, a very active season typically results (if there is no El Niño event present.)


Figure 1. The departure of sea surface temperature (SST) from average for March 7, 2010, as derived from the AMSR and AVHRR satellite data. Image credit: NOAA.

SSTs in the Main Development Region (10°N to 20°N and 20°W to 85°W) were an eye-opening 1.02°C above average during February. This easily beats the previous record of 0.83°C set in 1998. SSTs in the Main Development Region are already warmer than they were during June of last year, which is pretty remarkable, considering February is usually the coldest month of the year for SSTs in the North Atlantic. The 1.02°C anomaly is the 6th highest monthly SST anomaly for the MDR on record. The only other months with higher anomalies all occurred during 2005 (April, May, June, July, and September 2005 had anomalies of 1.06°C - 1.23°C).

What is responsible for the high SSTs?
Don't blame El Niño for the high Atlantic SSTs. El Niño is a warming of the Pacific waters near the Equator, and has no direct impact on Atlantic SSTs. Instead, blame the Arctic Oscillation (AO) or its close cousin, the North Atlantic Oscillation (NAO). The AO and NAO are climate patterns in the North Atlantic Ocean related to fluctuations in the difference of sea-level pressure between the Icelandic Low and the Azores-Bermuda High. They are some of the oldest known climate oscillations; seafaring Scandinavians described the pattern several centuries ago. Through east-west oscillation motions of the Icelandic Low and the Azores-Bermuda High, the AO/NAO controls the strength and direction of westerly winds and storm tracks across the North Atlantic. A large difference in the pressure between Iceland and the Azores (positive NAO) leads to increased westerly winds and mild and wet winters in Europe. Positive NAO conditions also cause the Icelandic Low to draw a stronger south-westerly flow of air over eastern North America, preventing Arctic air from plunging southward. In contrast, if the difference in sea-level pressure between Iceland and the Azores is small (negative NAO), westerly winds are suppressed, allowing Arctic air to spill southwards into eastern North America more readily. The winter of 2009 - 2010 has seen the most negative AO and NAO patterns since record keeping began in 1950, which caused a very cold winter in Florida and surrounding states. A negative AO/NAO implies a very weak Azores-Bermuda High, which reduces the trade winds circulating around the High. During December - February, trade winds between Africa and the Lesser Antilles Islands in the hurricane Main Development Region were 1 - 2 m/s (2.2 - 4.5 mph) below average (Figure 2). Slower trade winds mean less mixing of the surface waters with cooler waters down deep, plus less evaporational cooling of the surface water. As a result, the ocean has heated up significantly, relative to normal, over the winter. This heating is superimposed on the very warm global SSTs we've been seeing over the past decade, leading to the current record warmth. Global and Northern Hemisphere SSTs were the 2nd warmest on record in both December and January.


Figure 2. Sea level pressure averaged for the period December 2009 - February 2010 (left) and the sea level pressure averaged for the period December - February from the long-term mean (1968 - 1998). This winter, the Azores-Bermuda High was about 3 - 4 mb weaker than in a typical winter, due to strongly negative AO/NAO conditions. Image credit: NOAA/ESRL.


Figure 3. Departure of surface wind speed from average for December 2009 - February 2010. Winds were about 1 - 2 m/s (2.2 - 4.5 mph) lower than average over the Atlantic hurricane Main Development Region (MDR). Image credit: NOAA/ESRL.

What does this imply for the coming hurricane season?
According to Dr. Phil Klotzbach of the University of Colorado, February temperatures in the MDR are not strongly correlated with active hurricane seasons. The mathematical correlation between hurricane season Accumulated Cyclone Energy (ACE) and February SSTs is only 0.26, which is considered weak. Past hurricane seasons that had high February SST anomalies include 1998 (0.83°C anomaly), 2007 (0.71°C anomaly), and 1958 (0.68°C anomaly). These three years averaged 13 named storms, 8 hurricanes, and 3 intense hurricanes, which is considerably higher than the average of 10, 6, and 2. The big question is, how long will the strong negative AO/NAO conditions keep the Azores-Bermuda High weak? Well, the AO has risen to near-neutral values over the past week, and the latest 2-week forecast from the GFS model show that the AO and NAO will not be as strongly negative during March. This should allow the Azores-Bermuda High to strengthen some this month and increase the trade winds over the MDR. However, I still expect we'll set a record for warmest-ever March SSTs in the Main Development Region. Longer term, the crystal ball is very fuzzy, as our ability to predict the weather months in advance is poor. The long-range NOAA CFS model is predicting SSTs in the Atlantic MDR will be about 0.70°C above average during the peak months of hurricane season, making it one of the top five warmest years on record--but not as warm as the unbelievable Hurricane Season of 2005, which averaged 0.95°C above normal during August - October. The other big question is, when will El Niño fade? El Niño is currently holding steady at moderate intensity, and I expect that will continue through at least mid-April. It is possible El Niño will linger long enough into the year that it will create increased wind shear that will suppress this year's hurricane season.

Brazilian disturbance
An area of disturbed weather off the coast of Brazil, near 24S 36W, has changed little over the past two days. This disturbance still has a slight potential to develop into subtropical or tropical depression by Wednesday, according to the latest runs of the ECMWF, GFS, and NOGAPS models. Satellite imagery shows little organization to the cloud pattern, and only limited heavy thunderstorm activity. Wind shear over the region is about 20 knots, which is rather high, and should keep any development slow. Sea surface temperatures are about 27°C, about 1°C above average, which is warm enough to support a tropical storm. The system is small, limiting its potential to become a tropical cyclone. I don't think it will become a subtropical depression.

I'll have a new post on Wednesday.
Jeff Masters

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251. xcool
hey all.
Member Since: September 26, 2009 Posts: 2 Comments: 15626
250. HadesGodWyvern (Mod)
Seychelles Meteorological Services
Tropical Disturbance Advisory Number ONE
PERTURBATION TROPICALE 13-20092010
10:00 AM Réunion March 9 2010
====================================

At 6:00 AM UTC, Tropical Disturbance 13R (1005 hPa) located at 19.5S 50.9E has 10 minute sustained winds of 25 knots with gusts of 35 knots. The disturbance is reported as quasi-stationary.

Dvorak Intensity: T2.0

Forecast and Intensity
=====================
12 HRS: 20.0S 50.7E - 25 knots (Perturbation Tropicale)
24 HRS: 20.0S 50.2E - 30 knots (Depression Tropicale)
48 HRS: 18.6S 49.0E - (Depression sur terre)

Additional Information
=======================
System could continue to intensify up to the moderate tropical storm stage within the next 36 hrs before landfall over the eastern coast of Madagascar.

Improved low levels tradeward inflow and no wind shear and good divergence under upper level high pressures. System could reach moderate tropical storm stage. System should remain quasi stationary or slow moving southward drift then keep on a track west-northwest under the steering influence of low and mid level highs. Landfall is expected between 36-48 hrs over Malagasy coast.

Member Since: May 24, 2006 Posts: 50 Comments: 44881
I'm waiting in your room, t-dude! :)
Member Since: August 26, 2006 Posts: 10 Comments: 3620
Quoting tornadodude:


Hey Oz,

Yeah I saw the email but only glanced at it, didnt have the time to figure it out haha

yeah, and did you hear that my car will be fixed by friday?

that means I can begin chasing next week, although I have yet to get a camera and internet :p


Changed my mind...live chat you know where!
Member Since: August 26, 2006 Posts: 10 Comments: 3620
Quoting tornadodude:


Hey Oz,

Yeah I saw the email but only glanced at it, didnt have the time to figure it out haha

yeah, and did you hear that my car will be fixed by friday?

that means I can begin chasing next week, although I have yet to get a camera and internet :p


I'm tempted to send you my stuff...

e-mail...
Member Since: August 26, 2006 Posts: 10 Comments: 3620
I have trouble believing that, given the newer research (repeated for context) that there is not a link.

Rotating sunspots produce almost 300% more energy (Maria D. Kazachenko et al 2009 ApJ 704 1146-1158).

The previous 11-year sub-cycle (cycle 23) that started in 1997 had 12% more rotating sunspots in the Northern hemisphere during the peak and the most rotating sunspots on record (X. L. Yan et al 2008 ApJ 682 L65-L68).

Member Since: Posts: Comments:
Quoting Seastep:


We do not know that. Rotation was not really a consideration in studies that I am aware of. Seems it is quite significant and needs to be looked at. It's just starting to be looked at, relatively speaking. All research I know, relating to the topic, is purely # of spots.

Completely open if you have something to the contrary. Would love to read it.
Ok need to do research to respond. Back at you later, going down for count.
Member Since: Posts: Comments:
Quoting centex:
I know it's not simple, but looking at 1000's of years of data it's not sunspot cycles.


We do not know that. Rotation was not really a consideration in studies that I am aware of. Seems it is quite significant and needs to be looked at. It's just starting to be looked at, relatively speaking. All research I know, relating to the topic, is purely # of spots.

Completely open if you have something to the contrary. Would love to read it.
Member Since: Posts: Comments:
Quoting CycloneOz:
Wassup t'dude?

Geez man, I've got some serious stuff to pull off in the next two weeks. I sent you a CC email today I wrote to our streaming service provider. Testing begins ASAP....

Server issues tonight. SQL database updates not happening yet due to SSL certificate issues.

It's a mess, but I think I can sort it out...

I'm contemplating upgrading your web cam capability myself, and starting the stream service early to include "your" season...

Everything hinges on the SQL issues being resolved in short order...

Wish me luck!
What updates are not happening? I've never had web cam images posted on regular basis but the real time flash data for weather station has worked well.
Member Since: Posts: Comments:
Quoting CycloneOz:
Wassup t'dude?

Geez man, I've got some serious stuff to pull off in the next two weeks. I sent you a CC email today I wrote to our streaming service provider. Testing begins ASAP....

Server issues tonight. SQL database updates not happening yet due to SSL certificate issues.

It's a mess, but I think I can sort it out...

I'm contemplating upgrading your web cam capability myself, and starting the stream service early to include "your" season...

Everything hinges on the SQL issues being resolved in short order...

Wish me luck!


Hey Oz,

Yeah I saw the email but only glanced at it, didnt have the time to figure it out haha

yeah, and did you hear that my car will be fixed by friday?

that means I can begin chasing next week, although I have yet to get a camera and internet :p
Member Since: June 28, 2006 Posts: 24 Comments: 8201
Wassup t'dude?

Geez man, I've got some serious stuff to pull off in the next two weeks. I sent you a CC email today I wrote to our streaming service provider. Testing begins ASAP....

Server issues tonight. SQL database updates not happening yet due to SSL certificate issues.

It's a mess, but I think I can sort it out...

I'm contemplating upgrading your web cam capability myself, and starting the stream service early to include "your" season...

Everything hinges on the SQL issues being resolved in short order...

Wish me luck!
Member Since: August 26, 2006 Posts: 10 Comments: 3620
Quoting Seastep:
Here's some relatively new research centex.

Rotating sunspots produce almost 300% more energy (Maria D. Kazachenko et al 2009 ApJ 704 1146-1158).

The previous 11-year sub-cycle (cycle 23) that started in 1997 had 12% more rotating sunspots in the Northern hemisphere during the peak and the most rotating sunspots on record (X. L. Yan et al 2008 ApJ 682 L65-L68).

I know it's not simple, but looking at 1000's of years of data it's not sunspot cycles.
Member Since: Posts: Comments:
Here is an update from Oklahoma on today's unforecasted weather event:

Well what a weather event occurred in Western Oklahoma today guys. From quarter size hail to damaging winds to a crazy violent and damaging tornado. The tornado stayed well away from Oklahoma City, but for one small town, the town of Hammon, Oklahoma, wasn't so fortunate. Hammon, Oklahoma sustained some pretty intense damage from this tornado. To most of the storm chasers the damage was catastrophic. Five houses, a warehouse, and a barn were completely destroyed. The storm spotters that were in the area at the time said that this tornado looked like it carried EF-2- EF-3 intensity as the tornado entered the southwest corner of Hammon, Oklahoma at around six o'clock this evening. "As El Nino is currently weakening in the southern hemisphere the severe weather in the northern hemisphere may turn into one of the biggest outbreaks of the century," said a NOAA corresponder. Thankfully there were no fatalities reported, but I urge u all to pray for all of the tornado victims and that they may be able to get back to their normal lives soon. Personally I am not gonna get to excited about this season until the day of the severe weather events. Well that is what has gone on here in Oklahoma today. Stay tuned for another possible severe weather threat across Oklahoma for Wednesday.

Braxton Snow
Member Since: August 26, 2006 Posts: 10 Comments: 3620
No facts here but my wife thinks western US is due big earthquake. I know global size average happening but my women listening instincts really wonder. One plate moves and puts pressure on others..
Member Since: Posts: Comments:
Here's some relatively new research centex.

Rotating sunspots produce almost 300% more energy (Maria D. Kazachenko et al 2009 ApJ 704 1146-1158).

The previous 11-year sub-cycle (cycle 23) that started in 1997 had 12% more rotating sunspots in the Northern hemisphere during the peak and the most rotating sunspots on record (X. L. Yan et al 2008 ApJ 682 L65-L68).

Member Since: Posts: Comments:
*cite

;)
Member Since: June 28, 2006 Posts: 24 Comments: 8201
O hey Seastep,

You have mail, thanks!
Member Since: June 28, 2006 Posts: 24 Comments: 8201
Quoting MTWX:

Amen to that!! I lived in Leavenworth, KS


oh ok cool!

Such a sight, day or night, it is so incredible and awe inspiring
Member Since: June 28, 2006 Posts: 24 Comments: 8201
232. MTWX
Quoting tornadodude:


I have family out in Colby, Kansas, and yes, nothing beats a supercell out on the plains, such a gorgeous sight!

Amen to that!! I lived in Leavenworth, KS
Member Since: July 20, 2009 Posts: 23 Comments: 1392
Member Since: Posts: Comments:
Quoting MTWX:
I lived in Kansas for 5 years when I was a little tike. I think that is when I fell in love with severe weather. The years I've been here in Mississippi have really opened my eyes to hurricanes.


I have family out in Colby, Kansas, and yes, nothing beats a supercell out on the plains, such a gorgeous sight!
Member Since: June 28, 2006 Posts: 24 Comments: 8201
229. MTWX
I lived in Kansas for 5 years when I was a little tike. I think that is when I fell in love with severe weather. The years I've been here in Mississippi have really opened my eyes to hurricanes.
Member Since: July 20, 2009 Posts: 23 Comments: 1392
Quoting KEEPEROFTHEGATE:
maybe a few rumbles of thunder one could be heavy

Yep, the local met said to fix our gutters and downspouts after Snowmageddon (I wonder what he was doing in my backyard)!
Quoting PcolaDan:


I started to, but dozed off at 3, so gave up. :)

zzzzzzzzzzzzzzzz
Me too -- too much Academy Awards last night...good nite, all!
Member Since: Posts: Comments:
Quoting MTWX:

I'm an Air Force Brat. I was born in Kentucky, then spent time in a few other places. Spent a great deal of time in Montana (the place I call home), and have spent the last 6 years in Mississippi ( 1 year in Biloxi and 5 in Columbus)


oh wow, so you've gotten around haha

I have never been to Mississippi or Florida :p
Member Since: June 28, 2006 Posts: 24 Comments: 8201
226. MTWX
Quoting tornadodude:


oh ok, thats way up north.

TampaSpin is also originally from Indiana,

although I am originally from Texas

I'm an Air Force Brat. I was born in Kentucky, then spent time in a few other places. Spent a great deal of time in Montana (the place I call home), and have spent the last 6 years in Mississippi ( 1 year in Biloxi and 5 in Columbus)
Member Since: July 20, 2009 Posts: 23 Comments: 1392
Quoting MTWX:

Valparaiso


oh ok, thats way up north.

TampaSpin is also originally from Indiana,
actually he is from about 13 miles from where I live when I'm not at Purdue

although I am originally from Texas
Member Since: June 28, 2006 Posts: 24 Comments: 8201
Quoting PcolaDan:


I started to, but dozed off at 3, so gave up. :)


LOL.
Member Since: Posts: Comments:
Thanks KOTG. LOL. Only could see the lower left because I was looking for a 2.
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Quoting MTWX:

please tell me you really didn't count all those!! LOL


I started to, but dozed off at 3, so gave up. :)
Member Since: Posts: Comments:
221. MTWX
Quoting tornadodude:


Well I am currently undecided Lol

where in Indiana is she from?

Valparaiso
Member Since: July 20, 2009 Posts: 23 Comments: 1392
220. MTWX
Quoting PcolaDan:


1,492 brown dots 1/3 dark/med/light brown each, and 74 green dots 1/3 dark/med/light green each. Did I win? :)

please tell me you really didn't count all those!! LOL
Member Since: July 20, 2009 Posts: 23 Comments: 1392
Quoting MTWX:

Great School!! Let me guess Meteorology Major. I've been through that area quite a few times my wife is from Indiana


Well I am currently undecided Lol

where in Indiana is she from?
Member Since: June 28, 2006 Posts: 24 Comments: 8201
Quoting Seastep:
They're all 2 aren't they?

If I concentrate, I can see it in the lower left.
yes all two's
Member Since: Posts: Comments:
217. MTWX
Quoting Seastep:


It is fascinating to me, for obvious reasons. I cannot see that.

Here, I can see the 2 on both of the right hand pics, lower right tougher, but I see it.


My dad is color blind. He has problems with browns and reds. I'm an Electronics Technician, so my job kinda requires me not to be color blind
Member Since: July 20, 2009 Posts: 23 Comments: 1392
Quoting Seastep:


It is fascinating to me, for obvious reasons. I cannot see that.

Here, I can see the 2 on both of the right hand pics, lower right tougher, but I see it.



Wow, I have excellent color vision, but that bottom left is tough to see. Used to have excellent sight and hearing too. Stoopid aging.
Member Since: Posts: Comments:
They're all 2 aren't they?

If I concentrate, I can see it in the lower left.
Member Since: Posts: Comments:
i see all 4 2's
Member Since: Posts: Comments:
Quoting Seastep:
Unisys is my new best friend. No barbs.

I figured it out after all these years. Isn't so much color-blindness (although the underlying concept makes sense), it's the barbs.

Ike and the many others, look at maps w/o the barbs. Saves the half hour finding your state.

Just go here and go to the appropriate frame, or just check out the run, of what was posted.

Can I lobby for barb-free model runs? Would save me and 10% of the male population a lot of trouble. :)

Don't see much of a reason for the barbs on models anyway.

I see a bunch of dots here:



1,492 brown dots 1/3 dark/med/light brown each, and 74 green dots 1/3 dark/med/light green each. Did I win? :)
Member Since: Posts: Comments:
Quoting MTWX:

74


It is fascinating to me, for obvious reasons. I cannot see that.

Here, I can see the 2 on both of the right hand pics, lower right tougher, but I see it.

Member Since: Posts: Comments:
Quoting AwakeInMaryland:
Rumble on Friday night:
Link

Showers, maybe a rumble of thunder. Highs in the mid 60s and lows in the mid 50s.
maybe a few rumbles of thunder one could be heavy
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210. MTWX
Quoting tornadodude:



Lol Currently at Purdue, so in Indiana

Great School!! Let me guess Meteorology Major. I've been through that area quite a few times my wife is from Indiana
Member Since: July 20, 2009 Posts: 23 Comments: 1392
Quoting AstroHurricane001:
I heard that the storm in the Midwest could produce a few thunderstrms across the US. Could that same storm give us some early-season thunderstorms in S. Ontario? I'm supposed to go skiing on Friday in the midst of RAIN.
late thur into fri morn best chance for a rumble or two of thunder rain may be heavy fri from after daylight till before sunset
Member Since: Posts: Comments:
208. MTWX
Quoting Seastep:
Unisys is my new best friend. No barbs.

I figured it out after all these years. Isn't so much color-blindness (although the underlying concept makes sense), it's the barbs.

Ike and the many others, look at maps w/o the barbs. Saves the half hour finding your state.

Just go here and go to the appropriate frame, or just check out the run, of what was posted.

Can I lobby for barb-free model runs? Would save me and 10% of the male population a lot of trouble. :)

Don't see much of a reason for the barbs on models anyway.

I see a bunch of dots here:


74
Member Since: July 20, 2009 Posts: 23 Comments: 1392
Member Since: June 28, 2006 Posts: 24 Comments: 8201
Atmo spurred that with this, although it only took me about 5min on that one. ;)



Not as bad as the NHC, though.
Member Since: Posts: Comments:
Quoting MTWX:
LOL!! Where are you at tornadodude??



Lol Currently at Purdue, so in Indiana
Member Since: June 28, 2006 Posts: 24 Comments: 8201
Rumble on Friday night:
Link

Showers, maybe a rumble of thunder. Highs in the mid 60s and lows in the mid 50s.
Member Since: Posts: Comments:
Unisys is my new best friend. No barbs.

I figured it out after all these years. Isn't so much color-blindness (although the underlying concept makes sense), it's the barbs.

Ike and the many others, look at maps w/o the barbs. Saves the half hour finding your state.

Just go here and go to the appropriate frame, or just check out the run, of what was posted.

Can I lobby for barb-free model runs? Would save me and 10% of the male population a lot of trouble. :)

Don't see much of a reason for the barbs on models anyway.

I see a bunch of dots here:

Member Since: Posts: Comments:
202. MTWX
LOL!! Where are you at tornadodude??
Member Since: July 20, 2009 Posts: 23 Comments: 1392
LOL Atmo,

great minds think alike!
Member Since: June 28, 2006 Posts: 24 Comments: 8201

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About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.